1. Field of the Invention
The present invention relates generally to a device and method for preprocessing an image signal, and in particular, to a preprocessing device and method for determining whether or not an image is blurred, prior to recognizing characters in the image.
2. Description of the Related Art
Generally, a preprocessing operation is performed to recognize characters in an image. The “preprocessing operation” refers to an operation of processing an image before recognition of characters in the image occurs. The image preprocessing operation can include an operation of determining whether or not an input image is appropriate for character recognition, correcting a skew of an input image, properly correcting a size of an input image, and binarizing an image signal so that characters of the image signal can be recognized.
An image input for the preprocessing can be an image photographed through a camera. When an object is defocused or irregularly illuminated during photographing, the photographed image becomes blurred. Recognizing characters in such a blurred image causes an increase in the misrecognition rate. Therefore, it is preferable to determine whether or not an input image is blurred, before recognizing characters in the image. If a resolution of the image is too low to recognize characters therein, it is preferable to interrupt a recognition operation and then request re-input of the image.